BACKGROUND The alteration of lipid metabolism in cancer cells is recognized as one of the most important metabolic hallmarks of cancer. Membrane rafts defined as plasma membrane microdomains enriched in cholesterol and sphingolipids serve as platforms for signaling regulation in cancer. The main purpose of this study was to evaluate the effect of the cholesterol metabolite, 4-cholesten-3-one, on lipid metabolism and membrane raft integrity in two breast cancer cell lines, MCF-7 and MDA-MB-231. Its ability to reduce cell viability and migration has also been investigated. METHODS RT-qPCR was performed to evaluate the expression of enzymes involved in lipogenesis and cholesterol synthesis, and ABCG1 and ABCA1 transporters involved in cholesterol efflux. Its effect on cell viability and migration was studied using the MTT assay, the wound healing assay and the Transwell migration assay, respectively. The effect of 4-cholesten-3-one on membrane rafts integrity was investigated by studying the protein expression of flotillin-2, a membrane raft marker, and raft-enriched EGFR by western blot. RESULTS Interestingly, we found that 4-cholesten-3-one treatment decreased mRNA expression of different enzymes including ACC1, FASN, SCD1 and HMGCR. We further demonstrated that 4-cholesten-3-one increased the expression of ABCG1 and ABCA1. We also found that 4-cholesten-3-one decreased the viability of MCF-7 and MDA-MB-231 cells. This effect was neutralized after treatment with LXR inverse agonist or after LXRβ knockdown by siRNA. As a result, we also demonstrated that 4-cholesten-3-one disrupts membrane rafts and cell migration capacity. CONCLUSION Our results show that 4-cholesten-3-one exerts promising antitumor activity by altering LXR-dependent lipid metabolism in breast cancer cells without increasing lipogenesis.

中文翻译：

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4-cholesten-3-one通过减少脂肪生成和增强LXR依赖性胆固醇转运蛋白，降低乳腺癌细胞的活力并改变膜筏定位的EGFR表达。

背景技术癌细胞中脂质代谢的改变被认为是癌症最重要的代谢标志之一。膜筏定义为富含胆固醇和鞘脂的质膜微区，可作为癌症信号传导的平台。这项研究的主要目的是评估胆固醇代谢产物4-cholesten-3-one对两种乳腺癌细胞MCF-7和MDA-MB-231的脂质代谢和膜筏完整性的影响。还已经研究了其降低细胞活力和迁移的能力。方法采用RT-qPCR检测脂肪形成和胆固醇合成中酶的表达，以及胆固醇流出的ABCG1和ABCA1转运蛋白。使用MTT分析法研究了其对细胞活力和迁移的影响，伤口愈合测定法和Transwell迁移测定法。通过western blot研究flotilin-2，膜筏标记物和富筏表皮生长因子受体的蛋白表达，研究了4-胆甾烯-3-酮对膜筏完整性的影响。结果有趣的是，我们发现4-cholesten-3-one处理可降低ACC1，FASN，SCD1和HMGCR等不同酶的mRNA表达。我们进一步证明4-胆甾烯-3-酮增加了ABCG1和ABCA1的表达。我们还发现4-cholesten-3-one降低了MCF-7和MDA-MB-231细胞的生存能力。在用LXR反向激动剂治疗后或通过siRNA敲低LXRβ后，该作用被中和。结果，我们还证明了4-胆甾烯-3-酮可破坏膜筏和细胞迁移能力。